Thermoacoustic Driven Compressor

ABSTRACT

The present disclosure details a thermoacoustic driven compressor having a pressurized housing, which contains within a thermoacoustic engine and a working gas, coupled to a positive displacement reciprocating compressor. The thermoacoustic driven compressor generates scalable compressed air from a given heat source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/378,863, filed Feb. 20, 2009, which is incorporated hereinby reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

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INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to systems and methods for utilizing athermoacoustic engine with a positive displacement reciprocatingcompressor.

2. Background of the Invention

Due to the increasing costs and environmental concerns associated withhydrocarbon-based energy, society has recently shown greater interest intechnologies that promote energy efficiency and alternative sources ofenergy. One technology that shows great promise in both fields is athermoacoustic prime mover, which converts heat from any source toacoustic energy (i.e., an acoustic pressure wave).

In general, a thermoacoustic engine consists of a hermetically sealedcylinder housing (often referred to as a resonating tube) containing apressurized noble gas (e.g., helium or argon). Attached to the innerwall of the cylinder housing is the thermoacoustic engine core.Depending on the configuration, the engine core can induce either astanding or traveling pressure wave in the gas medium.

In the standing wave case, the engine core can consist of a stacksandwiched between a hot and cold exchanger. The stack typically is aporous solid spanning both temperature extremes through which gasoscillates. One characteristic of such a stack is that the pores of thestack are similar in size to the thermal penetration depth of the gas.To start the engine, hot and cold sources are applied to the hot andcold exchangers, respectively. The large temperature gradient createdbetween these two exchangers causes the gas in the stack to channel heatfrom the hot to the cold end (per the Second Law of Thermodynamics).This oscillating expansion and contraction of gas between exchangers iswhat creates the acoustic pressure wave. The standing wave time phasingcharacteristics are due to very poor thermal contact between the gas andthe stack (e.g., because of large pore size), which allows gas pressureand relative gas displacement oscillations to be in phase with the gasthermal expansion and contraction.

In contrast to a stack-derived thermoacoustic engine core, a travelingwave engine core incorporates a regenerator, which can also besandwiched between a hot and cold exchanger. The regenerator, just likethe stack, is typically a porous solid spanning both temperatureextremes through which gas oscillates. However, in this case the poresare usually much smaller than the thermal penetration depth of the gas.The excellent contact between the porous material and the gas providesfor more efficient heat transfer. The improved efficiency allows theoscillating gas thermal expansions and contractions to be in phase withthe gas pressure and relative gas velocity oscillations. Anotherdifferentiating factor is that the regenerator functions as an amplifierof acoustic power. This acoustic power can be provided by a number ofdevices, including, but not limited to, a torus shaped resonator (see,e.g., U.S. Pat. Nos. 6,032,464 and 6,314,740), and a cascaded stack(see, e.g., U.S. Pat. No. 6,658,862). An alternative means offacilitating traveling wave time phasing with a regenerator is throughthe use of a bellows (see, e.g., U.S. Pat. No. 7,143,586 B2).

It is also known in the art that the pressure wave of a thermoacousticprime mover can be used to reciprocate a mass element (e.g., a piston;see Grant, “Investigation of the Physical Characteristics of a MassElement Resonator”, M.S. Thesis, Naval Postgraduate School, Monterey,Calif., 1992, National Technical Information Service ADA251792).Furthermore, an electrodynamic linear alternator can be used to convertthis mechanical energy to electrical energy (see, e.g., U.S. Pat. Nos.4,623,808 and 5,389,844). While much discussion has focused on usingthis electrical energy for space probes and to a lesser extent gridpower, one application that has greater potential is electricalcompression. Unfortunately, for larger scale compression purposes, thisconfiguration is not practical due to the cost, complexity, and thelarge number of linear alternators needed.

A related field to the linear alternator is the linear motor compressor(see, e.g., U.S. Pat. No. 5,257,915). However, this device exhibitssimilar shortcomings, such as complexity and cost.

Therefore, it is apparent that there exists a need to generate largervolumes of compression on a more economical and robust scale viathermoacoustics.

SUMMARY OF THE INVENTION

The present disclosure provides a thermoacoustic compressor, comprisinga first housing having a first end, a second end, an inner wall, and anouter wall, the first housing defining a first cavity, and the secondend of the first housing defining a first piston rod aperture, a secondhousing having a first end, a second end, an inner wall, and an outerwall, the first end of the second housing operably connected to thesecond end of the first housing, the second housing comprisingpressurized gas or fluid and defining a second cavity, and the first endof the second housing defining a second piston rod aperture, areciprocating piston axially movable within the first and secondcavities, the reciprocating piston comprising a compression piston headhaving a first end, a second end, and an outer wall, the compressionpiston head disposed in the first cavity, the first end of thecompression piston head and the first end of the first housing defininga first variable-volume chamber, and the second end of the compressionpiston head and the second end of the first housing defining a secondvariable-volume chamber, a piston rod having a first end and a secondend, the first end of the piston rod connected to the second end of thecompression piston head, and a resonating piston head having a firstend, a second end, and an outer wall, the resonating piston headdisposed in the second cavity, the first end of the resonating pistonhead and the first end of the second housing defining a thirdvariable-volume chamber, and the second end of the resonating pistonhead and the second end of the second housing defining a fourthvariable-volume chamber, the first end of the resonating piston headconnected to the second end of the piston rod, a valved intake port anda valved discharge port on the first end of the first housing, athermoacoustic engine connected to the inner wall of the second housingpositioned between the second end of the resonating piston head and thesecond end of the second housing, and, for example, perpendicular to theresonating piston head and spanning the cross-sectional area of thesecond housing, a means for inhibiting gas flow between the first andthe second housing, a means for providing or delivering heat to thethermoacoustic engine, and a means for removing heat from thethermoacoustic engine.

In certain embodiments, the compression piston head comprises at least afirst sealing means disposed between the outer wall of the compressionpiston head and the inner wall of the first housing. In particularembodiments, the at least a first sealing means of the compressionpiston head comprises at least a first piston ring disposed within afirst groove or seat formed in the outer wall of the compression pistonhead. In certain aspects, the at least a first piston ring is coated,for example with polytetrafluoroethylene. In further embodiments, the atleast a first piston ring is made from metal, for example cast iron,aluminum, or an alloy, a composite material, a plastic material, or acomposite plastic material, for example polytetrafluoroethylene,polyetheretherketone, or polyphenylene sulfide, or any combinationthereof. In particular aspects, the composite plastic material comprisesa filler, for example white glass, glass molybdenum, glass graphite,carbon, polyetheretherketone, bronze, bronze molybdenum, polyphenylenesulfide, molybdenum, or any combination thereof. In other embodiments,the compression piston head further comprises a biasing means disposedwithin the first groove for forcing the at least a first piston ringagainst the inner wall of the first housing.

In certain embodiments, the thermoacoustic compressor further comprisesa guiding means for guiding the compression piston head in the firstcavity. In particular aspects, the guiding means comprises at least afirst guide ring disposed within a second groove formed in the outerwall of the compression piston head. In further embodiments, the atleast a first guide ring is coated, for example withpolytetrafluoroethylene. In other embodiments, the at least a firstguide ring is made from metal, for example cast iron, aluminum, or analloy, a composite material, a plastic material, or a composite plasticmaterial, for example polytetrafluoroethylene, polyetheretherketone, orpolyphenylene sulfide, or any combination thereof. In certain aspects,the composite plastic material comprises a filler, for example whiteglass, glass molybdenum, glass graphite, carbon, polyetheretherketone,bronze, bronze molybdenum, polyphenylene sulfide, molybdenum, or anycombination thereof.

In particular embodiments, the compression piston head is coated, forexample with polytetrafluoroethylene. In other embodiments, thecompression piston head is lubricated, for example oil lubricated. Inthese embodiments, the compression piston head may further comprise ameans for removing lubricant from the inner wall of the first housing,for example at least a first scraper ring, which may be disposed withina third groove formed in the outer wall of the compression piston head.In certain embodiments, the thermoacoustic compressor further comprisesa collection chamber located proximal to the second end of the firsthousing. In these embodiments, the first housing may further comprise apressure lubricating system, which in certain aspects may comprise apump, a filter, a lubricant line, a lubricant dispenser, a spray nozzle,or any combination thereof.

In certain aspects, the first housing, second housing, and/orreciprocating piston is made from metal, for example iron, cast iron,nodular cast iron, ductile iron, gray iron, aluminum, steel, cast steel,forged steel, stainless steel, for example 304, 316, 316L, 316H, 410, or419 stainless steel, carbon steel, bronze, an alloy, for example anickel-based alloy, such as a 625 alloy, an INCONEL® alloy, or anINCONEL® 625 alloy, or a combination thereof. In further embodiments,the inner wall of the first housing is coated, for example withpolytetrafluoroethylene. In other aspects, the first housing furthercomprises a cooling means, for example at least a first water jacketlocated around the first housing, at least a first water jacket locatedin a cavity between the inner wall and the outer wall of the firsthousing, and/or at least a first air fin located on the outer wall ofthe first housing.

In particular aspects, the thermoacoustic compressor further comprises adisplacement control and return means within the first housing, which incertain aspects may comprise at least a first mechanical spring locatedbetween the second end of the compression piston head and the second endof the first housing, or a variable-volume balance chamber within thefirst housing located between the second end of the compression pistonhead and the second end of the first housing. In these aspects, thethermoacoustic compressor may further comprise a porting means, forexample a groove in the inner wall of the first housing, in fluidcommunication between the variable-volume balance chamber and thevariable-volume compression chamber, or further comprise a mechanicalspring disposed in a groove in the inner wall of the variable-volumebalance chamber between the second end of the compression piston headand the second end of the first housing.

In certain embodiments, the means for inhibiting gas flow between thefirst and the second housings is a seal disposed about the piston rodand located in the first piston rod aperture or the second piston rodaperture. In particular aspects, the seal comprises packing, for examplean oil wiper or pressure packing, which may be cooled, for example watercooled or cooled using a heat conducting sleeve, such as aThermosleeve™. In these aspects, the thermoacoustic compressor mayfurther comprise a purging line connected to the oil wiper or pressurepacking and a purging canister, which may comprise the same pressurizedgas as the second housing, connected to the purging line comprisingpressurized gas or fluid, or may further comprise a venting lineconnected to the oil wiper or pressure packing and extending to anenvironment external of the first or second housing. In furtherembodiments, the venting line extends through the outer wall of thefirst or second housing.

In other embodiments, the first and/or second housing comprises at leasta first lubricating strip between the first and/or second housing andthe piston rod. In further embodiments, the second housing furthercomprises a displacement control and return means, which may comprise atleast a first mechanical spring located between the first end of theresonating piston head and the first end of the second housing, or avariable-volume balance chamber within the second housing locatedbetween the first end of the resonating piston head and the first end ofthe second housing, in which case the thermoacoustic compressor mayfurther comprise a mechanical spring disposed in a groove in the innerwall of the variable-volume balance chamber between the first end of theresonating piston head and the first end of the second housing. In yetother embodiments, the inner wall of the second housing and/orresonating piston head is coated, for example withpolytetrafluoroethylene. In still other embodiments, the resonatingpiston head is tightly fitted within the second cavity.

In further embodiments, the resonating piston head comprises at least afirst piston ring disposed within a first groove formed in the outerwall of the resonating piston head. In certain embodiments, the at leasta first piston ring is a piston sealing or guide ring. In particularaspects, the at least a first piston ring is coated, for example withpolytetrafluoroethylene. In other embodiments, the at least a firstpiston ring is made from metal, for example cast iron, aluminum, or analloy, a composite material, a plastic material, or a composite plasticmaterial, for example polytetrafluoroethylene, polyetheretherketone, orpolyphenylene sulfide, or any combination thereof. In yet otherembodiments, the composite plastic material comprises a filler, whichmay comprise white glass, glass molybdenum, glass graphite, carbon,polyetheretherketone, bronze, bronze molybdenum, polyphenylene sulfide,molybdenum, or any combination thereof. In additional embodiments, theresonating piston head further comprises a biasing means disposed withina first groove formed in the outer wall of the resonating piston headfor forcing the at least a first piston ring against the inner wall ofthe second housing.

In certain embodiments, the means for providing or delivering heat tothe thermoacoustic engine comprises heating metal wiring. In otherembodiments, the means for providing or delivering heat to thethermoacoustic engine comprises a heated fluid and piping. In suchembodiments, the means for providing or delivering heat to thethermoacoustic engine may further comprise a pump, may further comprisea heat recovery or exchanger unit, which may comprise pumping a heatedfluid through piping from a heat recovery or exchanger unit. In furtherembodiments, the means for removing heat from the thermoacoustic enginecomprises cooling fluid and piping. In these embodiments, the means forremoving heat from the thermoacoustic engine may further comprise apump, and further comprise a heat recovery or exchanger unit, which maycomprise pumping a cooling fluid through piping to a heat recovery orexchanger unit. In yet other embodiments, the means for removing heatfrom the thermoacoustic engine further comprises at least a first fan.

In particular aspects, the thermoacoustic compressor further comprises adehumidifying means, for example a scrubber, a desiccant dryer, or arefrigeration means, such as thermoacoustic or Stirling refrigeration,in fluid communication with the valved discharge port. In other aspects,the thermoacoustic compressor further comprises an intercooler in fluidcommunication with the valved discharge port, a pulsation tube in fluidcommunication with the valved discharge port, and/or a lubricantremoving means, which may comprise a coalescer, in fluid communicationwith the valved discharge port. In further aspects, the thermoacousticcompressor further comprises a means for storing compressed fluid influid communication with the valved discharge port, and/or a heatingmeans, for example a heat recovery unit or a heat exchanger, in fluidcommunication with the valved discharge port. In still further aspects,the thermoacoustic compressor further comprises a filter in fluidcommunication with the valved intake port, and/or a refrigeration means,for example thermoacoustic or Stirling refrigeration, in fluidcommunication with the valved intake port.

In certain embodiments, the thermoacoustic engine comprises athermoacoustic core. In such embodiments, the thermoacoustic core maycomprise a hot exchanger, which may comprise a shell-and-tube orfinned-tube design, a cold exchanger, which may comprise ashell-and-tube or finned-tube, or circulating heat exchanger design, anda stack. In particular embodiments, the hot and/or cold exchanger ismade from metal, for example stainless steel, such as 304 stainlesssteel, 316 stainless steel, 316L stainless steel, 316H stainless steel,409 stainless steel, or 419 stainless steel, or a combination thereof,carbon steel, aluminum, an alloy, for example a nickel-based alloy, anickel-based 625 alloy, or an INCONEL® 625 alloy, copper, telluriumcopper, oxygen-free high conductivity copper, or a combination thereof.In further embodiments, the stack comprises a honeycomb, stacked screen,parallel-plate, random fiber, foam, foil roll/stack, or packed spheredesign. In other aspects, the stack is made from carbon nanotubes, aceramic, a composite, glass, metal hydrides, phase exchange materials,nanoparticles, or metal, such as stainless steel, carbon steel,aluminum, an alloy, or a combination thereof. In other such embodiments,the thermoacoustic engine core may comprise a hot exchanger, a coldexchanger, and a regenerator. In these embodiments, the hot exchangermay be downstream of the regenerator. In certain aspects, theregenerator comprises a honeycomb, stacked screen, or parallel-platedesign. In other aspects, the regenerator is made from carbon nanotubesor metal, for example stainless steel, carbon steel, aluminum, an alloy,or a combination thereof.

In particular embodiments, the second housing comprises or defines atorus, which may define an acoustic compliance portion and an inertanceportion, which may comprise a polished inside surface and/or a pressurebalancing sliding joint. In these embodiments, the thermoacousticcompressor may further comprise a max flux suppressor within the torus,and/or a thermal buffer tube adjacent to the hot exchanger opposite theregenerator. In certain aspects, the thermal buffer tube is made fromcarbon nanotubes or metal, such as stainless steel, carbon steel,aluminum, an alloy, or a combination thereof. In other aspects, thethermal buffer tube comprises a polished inside surface, at least afirst flow straightener, and/or is tapered. In yet other aspects, thelength of the thermal buffer tube is greater than the peak-to-peak fluiddisplacement amplitude. In certain embodiments, the thermoacousticengine further comprises an ambient heat exchanger for residual heatleaks, and/or further comprises a bellows.

In certain embodiments, the resonating and/or compression piston head isflat, truncated cone-shaped, shaped like the cross-section of anisosceles trapezoid, hemi-elliptical shaped, or a combination thereof.In particular embodiments, the resonating and/or compression piston headis solid or hollow. In other embodiments, the thermoacoustic compressorfurther comprises a second valved intake port and a second valveddischarge port on the second end of the first housing. In still otherembodiments, the first end of the second housing is physically mated tothe second end of the first housing.

In additional embodiments, the thermoacoustic compressor furthercomprises a third housing having a first end, a second end, an innerwall, and an outer wall, the first end of the second housing operablyconnected to the second end of the third housing, the second end of thefirst housing operably connected to the first end of the third housing,the third housing defining a third cavity, the first end of the thirdhousing defining a third piston rod aperture, and the second end of thethird housing defining a fourth piston rod aperture. In particularaspects, the third housing further comprises a displacement control andreturn means, which may comprise at least a first mechanical spring, atleast a first gas spring, or at least a first mechanical spring and atleast a first gas spring. In further aspects, the third housing is madefrom metal, for example iron, cast iron, nodular cast iron, aluminum,steel, cast steel, forged steel, stainless steel, carbon steel, bronze,an alloy, or a combination thereof. In other aspects, the inner wall ofthe third housing is coated, for example with polytetrafluoroethylene.In yet other aspects, the inner wall of the third housing comprises acylinder liner, for example a replaceable cylinder liner. In still otheraspects, the cylinder liner is coated, for example withpolytetrafluoroethylene. In certain aspects, the third housing comprisesat least a first sealable access hole.

In other embodiments, the second housing further comprises a pluralityof thermoacoustic engines in series. In certain embodiments, the secondhousing further comprises at least one region of high specific acousticimpedance in an acoustic wave. In such embodiments, the second housingmay further comprise a plurality of thermoacoustic engines in serieswithin the at least one region of high specific acoustic impedance. Inparticular embodiments, the at least a first of the plurality ofthermoacoustic engines is a stack and at least a second of the pluralityof thermoacoustic engines is a regenerator. In other embodiments, thesecond housing defines a first area having a first cross-sectional areaand a second area having a second cross-sectional area. In suchembodiments, the cross-sectional area of the first cross-sectional areamay be the same or different than the cross-sectional area of the secondcross-sectional area. In yet other embodiments, the second housingfurther defines a third area having a third cross-sectional area betweenthe first area having a first cross-sectional area and the second areahaving a second cross-sectional area, thereby creating a plurality ofregions of high acoustic impedance. In still other embodiments, thethermoacoustic compressor comprises a thermal buffer tube adjacent to atleast one of the plurality of thermoacoustic engines. In certainaspects, the thermal buffer tube is tapered, while in other aspects thethermal buffer tube connects a first and a second of the plurality ofthermoacoustic engines. In further aspects, the second housing comprisesa plurality of regions of high specific acoustic impedance along acommon axis. In such aspects, the at least a first of the plurality ofregions of high specific acoustic impedance may comprise a plurality ofthermoacoustic engines in series and at least a second of the pluralityof regions of high specific acoustic impedance comprises a plurality ofthermoacoustic engines in series, or the at least a first and at least asecond of the plurality of regions of high specific acoustic impedancemay be separated by an acoustic side branch, thereby creating an axiallyextended region of high acoustic impedance.

In further embodiments, the first, second, and/or third housingcomprises at least a first sealable access hole. In other embodiments,the first, second and third housing each comprise at least a firstsealable access hole. In particular embodiments, the inner wall of thefirst, second, and/or third housing comprises a cylinder liner, forexample a replaceable cylinder liner and/or a coated cylinder liner. Inother embodiments, the intake and/or discharge valve is corrosionresistant, for example the intake valve may be made from stainlesssteel.

In certain aspects, the thermoacoustic compressor further comprises agas or fluid bearing disposed in a clearance gap between the outer wallof the compression piston and the inner wall of the first housing, whilein other aspects the thermoacoustic compressor further comprises a gasor fluid bearing disposed in a clearance gap between the outer wall ofthe resonating piston and the inner wall of the second housing. Inparticular aspects, the thermoacoustic compressor further comprises afirst gas or fluid bearing disposed in a clearance gap between the outerwall of the compression piston and the inner wall of the first housingand a second gas or fluid bearing disposed in a clearance gap betweenthe outer wall of the resonating piston and the inner wall of the secondhousing.

In other embodiments, the thermoacoustic compressor further comprises athird housing having a first end, a second end, an inner wall, and anouter wall, the third housing defining a third cavity, the second end ofthe third housing operably connected to the first end of the firsthousing, and the second end of the third housing defining a third pistonrod aperture, a second compression piston head having a first end, asecond end, and an outer wall, the second compression piston headdisposed in the third cavity, the first end of the second compressionpiston head and the first end of the third housing defining a fifthvariable-volume chamber, and the second end of the second compressionpiston head and the second end of the third housing defining a sixthvariable-volume chamber, a second piston rod having a first end and asecond end, the first end of the second piston rod connected to thefirst end of the compression piston head, and the second end of thesecond piston rod connected to the second end of the second compressionpiston head, and a second valved intake port and a second valveddischarge port on the first end of the third housing. In certainembodiments, the size of the third housing is the same or different fromthe size of the first housing. In further embodiments, the valveddischarge post of the first housing is in fluid communication with thesecond valved intake port of the third housing. In such embodiments, thethermoacoustic compressor may further comprise an intercooler in fluidcommunication with the valved discharge port.

The present disclosure also provides a multistage thermoacousticcompressor, comprising a first thermoacoustic compressor and a secondthermoacoustic compressor, wherein the valved discharge port of thefirst thermoacoustic compressor is in fluid communication with thevalved intake port of the second thermoacoustic compressor. In certainembodiments, the multistage thermoacoustic compressor further comprisesan intercooler in fluid communication with the valved discharge port ofthe first thermoacoustic compressor. In particular embodiments the firstthermoacoustic compressor is vertically aligned with the secondthermoacoustic compressor, while in other embodiments the firstthermoacoustic compressor is horizontally aligned with the secondthermoacoustic compressor.

The present disclosure further provides a thermoacoustic compressorcomprising a first housing having a first end, a second end, an innerwall, and an outer wall, the first housing defining a first cavity, andthe second end of the first housing defining a first piston rodaperture, a second housing having a first end, a second end, an innerwall, and an outer wall, the first end of the second housing operablyconnected to the second end of the first housing, the second housingcomprising pressurized gas or fluid and defining a second cavity, andthe first end of the second housing defining a second piston rodaperture, a third housing having a first end, a second end, an innerwall, and an outer wall, the second end of the third housing operablyconnected to the first end of the first housing, the third housingcomprising pressurized gas or fluid and defining a third cavity, and thesecond end of the third housing defining a third piston rod aperture, areciprocating piston axially movable within the first and secondcavities, the reciprocating piston comprising, a compression piston headhaving a first end, a second end, and an outer wall, the compressionpiston head disposed in the first cavity, the first end of thecompression piston head and the first end of the first housing defininga first variable-volume chamber, and the second end of the compressionpiston head and the second end of the first housing defining a secondvariable-volume chamber, a first piston rod having a first end and asecond end, the first end of the first piston rod connected to thesecond end of the compression piston head, a first resonating pistonhead having a first end, a second end, and an outer wall, the firstresonating piston head disposed in the second cavity, the first end ofthe first resonating piston head and the first end of the second housingdefining a third variable-volume chamber, and the second end of thefirst resonating piston head and the second end of the second housingdefining a fourth variable-volume chamber, the first end of the firstresonating piston head connected to the second end of the first pistonrod, a second piston rod having a first end and a second end, the secondend of the second piston rod connected to the first end of thecompression piston head, and a second resonating piston head having afirst end, a second end, and an outer wall, the second resonating pistonhead disposed in the third cavity, the first end of the secondresonating piston head and the first end of the third housing defining afifth variable-volume chamber, and the second end of the secondresonating piston head and the second end of the third housing defininga sixth variable-volume chamber, the second end of the second resonatingpiston head connected to the first end of the second piston rod, a firstvalved intake port and a first valved discharge port on the first end ofthe first housing, a first thermoacoustic engine connected to the innerwall of the second housing positioned between the second end of thefirst resonating piston head and the second end of the second housing, asecond thermoacoustic engine connected to the inner wall of the thirdhousing positioned between the first end of the second resonating pistonhead and the first end of the third housing, a means for inhibiting gasflow between the first and the second housing, a means for inhibitinggas flow between the first and the third housing, a means for providingor delivering heat to the first thermoacoustic engine, a means forproviding or delivering heat to the second thermoacoustic engine, ameans for removing heat from the first thermoacoustic engine, and ameans for removing heat from the second thermoacoustic engine. Incertain embodiments, the thermoacoustic compressor further comprises asecond valved intake port and a second valved discharge port on thesecond end of the first housing. In other embodiments, thethermoacoustic compressor further comprises a starting mechanismconnected to the first housing.

The present disclosure additionally provides a method of compressing afluid or gas, comprising, introducing a fluid or gas through the valvedintake port of a thermoacoustic compressor into the firstvariable-volume chamber of the first cavity, and running thethermoacoustic compressor, thereby compressing the fluid or gas. Incertain embodiments, the fluid or gas is filtered and/or refrigeratedprior to introduction into the first variable-volume chamber. Inparticular embodiments, the compressed fluid or gas is released from thefirst variable-volume chamber through the valved discharge port. Infurther embodiments, the compressed fluid or air is stored after releasefrom the first variable-volume chamber. In other embodiments, thecompressed fluid or gas is cooled or heated after release through thevalved discharge port. In yet other embodiments, the compressed fluid orgas is introduced into a compression chamber of a second thermoacousticcompressor.

In additional embodiments, the compressed fluid or gas is introducedinto a separate mechanical device, such as a gas turbine, an expanderattached to an electrical generation system, an expander connected to agas turbine power shaft, or a reciprocating engine. In furtherembodiments, heat is provided to the thermoacoustic engine from aseparate mechanical device, for example waste heat generated by theseparate mechanical device. In other embodiments, heat is provided tothe thermoacoustic engine from a separate industrial process, forexample waste heat generated by the separate industrial process. Inparticular embodiments heat is provided to the thermoacoustic enginefrom a separate alternative energy process, for example waste heatgenerated by the separate alternative energy process.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention, as claimed. In thisapplication, the use of the singular includes the plural, the word “a”or “an” may mean a singular object or element, or it may mean aplurality, at least one, or one or more of such objects or elements, andthe use of “or” means “and/or”, unless specifically stated otherwise.Throughout this disclosure, unless the context dictates otherwise, theword “comprise” or variations such as “comprises” or “comprising,” isunderstood to mean “includes, but is not limited to” such that otherelements that are not explicitly mentioned may also be included.Furthermore, the use of the term “including”, as well as other forms,such as “includes” and “included”, is not limiting. Also, terms such as“element” or “component” encompass both elements or componentscomprising one unit and elements or components that comprise more thanone unit unless specifically stated otherwise.

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described andclaimed. All documents, or portions of documents, cited in thisapplication, including, but not limited to, patents, patentapplications, articles, books, and treatises, are hereby expresslyincorporated herein by reference in their entirety for any purpose. Inthe event that one or more of the incorporated literature and similarmaterials defines a term in a manner that contradicts the definition ofthat term in this application, this application controls.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are included to further demonstrate certainaspects and embodiments of the present invention. The invention may bebetter understood by reference to one or more of these drawings incombination with the detailed description of specific embodimentspresented herein.

FIG. 1. A horizontal cross section through one embodiment of asingle-acting non-lubricated thermoacoustic compressor.

FIG. 2. A horizontal cross section through one embodiment of asingle-acting non-lubricated thermoacoustic compressor incorporating ameans of return behind the compression piston head.

FIG. 3. A schematic of one embodiment of a thermoacoustic drivencompressor/gas turbine system.

FIG. 4A, FIG. 4B, and FIG. 4C. FIG. 4A. A horizontal cross sectionthrough one embodiment of a single-acting non-lubricated compressionpiston head. FIG. 4B. A partial horizontal cross section through oneembodiment of a single-acting non-lubricated compression piston headusing a gas bearing system. FIG. 4C. A horizontal cross section throughone embodiment of a resonating piston head using a gas bearing system.

FIG. 5. A horizontal cross section through one embodiment of asingle-acting lubricated thermoacoustic compressor.

FIG. 6. A horizontal cross section through one embodiment of asingle-acting lubricated compression piston head.

FIG. 7A and FIG. 7B. FIG. 7A. A horizontal cross section through oneembodiment of a double-acting non-lubricated thermoacoustic drivencompressor incorporating a torus-derived thermoacoustic engine andtandem resonator at both ends of the compression piston head. FIG. 7B. Ahorizontal cross section through one embodiment of adouble-acting/single-acting non-lubricated/lubricated compression pistonhead.

FIG. 8. A horizontal cross section through one embodiment of adouble-acting lubricated thermoacoustic driven compressor incorporatinga cascaded thermoacoustic engine and a tandem resonator at both ends ofthe compression piston head.

FIG. 9. A horizontal cross section through a second embodiment of adouble-acting lubricated thermoacoustic driven compressor incorporatinga cascaded thermoacoustic engine and a tandem resonator at both ends ofthe compression piston head.

FIG. 10. Optional design of thermoacoustic end-housing with expandedcompliance section.

FIG. 11. A horizontal cross section through one embodiment of amultistage thermoacoustic driven compressor incorporating a tandemcompression head.

FIG. 12A and FIG. 12B. FIG. 12A. Schematic of a first horizontalorientation for single or multi-stage thermoacoustic compressors. FIG.12B. Schematic of a second horizontal orientation for single ormulti-stage thermoacoustic compressors.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure provides for a thermoacoustic driven compressor(“TADC”) that can utilize a heat driven standing or traveling wavethermoacoustic engine of any variation (e.g., requiring the use of astack, regenerator, torus, hybrid (e.g., cascade), bellows, or anyvariation thereof), to power any type of reciprocating compressor orpump. A general discussion follows of exemplary TADCs containing threehousings. These housings (thermoacoustic, distance, and compression) canhave multiple mating surfaces and means of connecting mating surfaces toeach other and/or to other structures. These housings can also bedifferent sizes, vary in shape, and be separate from each other. It willbe understood that the following discussion is not meant to be limiting,and that a TADC with greater or fewer housings or multiple components(from thermoacoustic, distance, compression, etc.) combined under onehousing are within the scope of the present invention. It will also beunderstood that TADC housings can be formed from multiple componentsmated together. Finally, it will be understood that a TADC can benon-lubricated, lubricated, single-acting, double-acting, single-stage,multi-stage, and can incorporate tandem compression pistons and rodsand/or a tandem resonating piston with accompanying piston rod andthermoacoustic engine(s).

Referring to the figures, FIG. 1 demonstrates one embodiment of asingle-acting non-lubricated TADC 101 comprised of a thermoacoustic 102,distance 110, and compression 117 housing. The thermoacoustic housing(resonating tube) 102 contains a pressurized compressible workingfluid/gas 126. Supported inside the thermoacoustic housing 102 is athermoacoustic engine core 103, which in this embodiment includes a hotexchanger 104, a cold exchanger 105, and a stack 106. When the hotexchanger 104 and cold exchanger 105 are connected to a hot source 128and cold source 129, respectively, a temperature differential is createdbetween the two exchangers, and the stack 106 facilitates this process.This temperature gradient enables the thermoacoustic engine to generatean acoustic pressure wave 127 via the working fluid/gas medium 126. Saidanother way, the pressurized working fluid/gas 126 expands and contractswithin the stack 106, moving heat from the hot exchanger 104 to the coldexchanger 105. In so doing, the oscillating gas 126 exhibits standingwave time phasing characteristics 127. This oscillating kinetic energy(e.g., an acoustic pressure wave) is converted to mechanical energy bymeans of a resonating piston head 107, which can have seated sealingand/or guiding rings (not shown), reciprocates linearly, and isconnected to a piston rod 108. In embodiments where pressure/lubricationpacking is not used (pressure/lubrication packing discussed in detailbelow), at locations where the piston rod 108 interacts with any of thehousings lubricating strips 109 can be attached to the housing to reducefriction.

The distance housing 110 contains a continuation of the linearlyreciprocating piston rod 108. As a means of controlling displacement,return, and centering of the piston assembly, one or more springs 111can be incorporated in the distance housing 110. The springs 111 can bemechanical (e.g., helix, double helix, or planar), gas, magnetic, or acombination thereof. Pressure packings 112 and 113, or any other type ofseal, can be set about the piston rod 108 and piston rod apertures 130and 131 at both ends of the distance housing 110 to inhibit gas/fluidleakage from the thermoacoustic housing 102 and compression housing 117via the piston rod 108. For the side of the distance housing 110 facingthe thermoacoustic housing 102, a purging line 114 and canister 115 canbe incorporated with pressure packing 112. The canister 115 can containthe same gas as that in the thermoacoustic housing 102, albeit at ahigher pressure (gas used to expand rings in pressure packing, therebyproviding a better seal) and can be attached to the exterior of thehousing 110. For the side of the distance housing 110 facing thecompression housing 117, a tube 116 may be attached to pressure packing113 to vent residual compressed gas, although a purging line andcanister could also be used (see FIG. 2).

The compression housing 117 contains the compression piston head 118,piston sealing and/or guide rings (not shown), a cavity or compressionchamber 119, the remaining portion of the linearly reciprocating pistonrod 108, water jackets 120 and 121 (optional; could also use air finstogether or separately (not shown)), gas/fluid inlet valve 122,gas/fluid discharge valve 123, gas/fluid inlet port 124, and gas/fluiddischarge port 125. As the compression piston head 118 is interconnectedby means of piston rod 108, the oscillating acoustic force applied tothe resonating piston head 107 propels the compression piston head 118forward (to the right in FIG. 1). As a result, the process gas/fluid inthe compression chamber 119 is compressed. When the pressure in thecompression chamber exceeds the discharge pressure, the processgas/fluid is released via the discharge valve 123. On the return stroke,in this case due to springs 111, the one-way inlet valve 122 opens sothat new process gas/fluid can enter the compression chamber.

FIG. 2 shows another embodiment of a single-acting non-lubricated TADC201. In this example, the thermoacoustic housing 202 (resonating tube)once again comprises a pressurized compressible working fluid/gas 226,and incorporates a regenerator 206, in lieu of a stack, in thethermoacoustic engine core 203. Additionally, the thermoacoustic housing202 is of a torus configuration that incorporates a compliance portion228 and an inertance tube 229. In traveling wave embodiments, the coldexchanger 205 is to the left of the hot exchanger 204 (with the coldexchanger 205 upstream of the regenerator 206). When the hot exchanger204 and cold exchanger 205 are connected to a hot source 236 and coldsource 235, respectively, a temperature differential is created betweenthe two exchangers. This temperature differential enables theregenerator 206 to amplify incoming acoustic power. This amplifiedacoustic power with traveling wave phasing 227 is then pumped out of thehot exchanger 204 and used to drive the linearly resonating piston head207 (sealing and/or guiding rings not shown), which is connected to apiston rod 208, and provide new acoustic power to the cold exchanger 205via the inertance tube 229 and compliance portion 228. One or morethermal buffer tubes (“TBT”) 230 can also be incorporated adjacent tothe hot exchanger 204 at multiple locations, thereby mitigating heatleaks (and corresponding efficiency loss) from the hot exchanger toambient. The regenerator 206 provides the same thermal isolation on theopposite side.

The distance housing 210 contains a continuation of the linearlyreciprocating piston rod 208. Additionally, pressure packing 212, withan accompanying purging canister 215 and a purging line 214, can be setabout the piston rod 208 and the distance housing piston rod aperture237 facing the thermoacoustic housing, and pressure packing 213, with anaccompanying purging canister 231 and a purging line 216, can be setabout the piston rod 208 and the distance housing piston rod aperture238 facing the compression housing.

The compression housing 217 contains the compression piston head 218,piston seals and/or guiding rings (not shown), a cavity or compressionchamber 219, the remaining portion of the linearly reciprocating pistonrod 208, water jackets 220 and 221 (optional), gas/fluid inlet valve222, gas/fluid discharge valve 223, gas/fluid inlet port 224, andgas/fluid discharge port 225. A spring can be incorporated in thecompression housing 217 as a means of controlling displacement, return,and centering of the compression piston head. This spring can be abalance chamber 232 (gas spring), which is located behind thecompression piston 218, one or more mechanical springs 233, and aporting mechanism 234 (one-way valve optional—not shown), or anycombination thereof. The gas spring 232 and mechanical spring 233 can beused to prevent the compression piston head 218 from contacting eitherend of the inner surface of the compression housing 217. The portingmechanism 234 (e.g., a groove) allows the compression chamber 219 andbalance chamber 232 to communicate during reciprocation of thecompression piston head 218, thereby further enabling the compressionpiston head 218 to stay centered. As the compression piston head 218 isinterconnected by means of piston rod 208, the oscillating acousticforce applied to the resonating piston head 207 propels the compressionpiston head 218 forward (to the right in FIG. 2). As a result, theprocess gas/fluid in the compression chamber 219 is compressed. When thepressure in the compression chamber exceeds the discharge pressure, theprocess gas/fluid is released via the discharge valve 223. On the returnstroke, in this case due to springs 232 and 233, the one-way inlet valve222 opens so that new process gas/fluid can enter the compressionchamber.

While not shown in the above mentioned figures, a cascaded derivedthermoacoustic engine or any variation/hybrid thereof could also be usedto power a non-lubricated single acting TADC. Furthermore, all of theabove mentioned compressors can incorporate a second set of valved inletand discharge ports, thereby allowing process gas/fluid to be compressedon both the forward and backward motion of the piston (double-acting).

The thermoacoustic housing can be fabricated from various materialsincluding, but not limited to, ceramics, composites, aluminum, steel,cast steel, forged steel, stainless steel (e.g., 304, 316, 316H, 316L,410, 419), carbon steel, alloys, including, but not limited to,nickel-based alloys (e.g., INCONEL® alloys), including, but not limitedto, alloy 625, or any combinations thereof. While the resonating tube iscylindrical as shown, other shapes are possible, and the resonating tubecan contain multiple sealable access holes. An oscillating side-branch(see, e.g., U.S. Pat. No. 6,560,970) may also be added to thethermoacoustic housing.

The working fluid or gas can be selected from any number of known fluidsor gases, including, but not limited to, inert gases, such as helium andargon. In general, the working fluid or gas should have a high speed ofsound, high thermal conductivity, a low Prandtl number, and benon-flammable.

In the thermoacoustic engine core, the hot exchanger and cold exchangercan take a variety of forms, including, but not limited to,shell-and-tube or finned-tube, or circulating heat exchanger design(see, e.g., U.S. Pat. No. 6,637,211), be in any order (in the case of astanding wave), have multiple units, and made from materials including,but not limited to, aluminum, aluminum alloy 6061, steel, cast steel,forged steel, stainless steel (e.g., 304, 316, 316H, 316L, 410, 419),carbon steel, alloys, including, but not limited to, nickel-based alloys(e.g., INCONEL® alloys), including, but not limited to, alloy 625,copper, oxygen-free high conductivity (“OFHC”) copper, tellurium copper,or any combination thereof. The stack and regenerator can also take avariety of forms, including, but not limited to, a honeycomb, stackedscreen, parallel-plate, random fiber, foam, foil roll/stack, or packedspheres design, and can be made from materials including, but notlimited to, aluminum, ceramic, composite, glass, metal hydrides, phasechange materials, nanoparticles, carbon nanotubes, stainless steel(e.g., 304, 316, 316L, 316H, 410, and 419), carbon steel, and alloys,including, but not limited to, nickel-based alloys (e.g., INCONEL®alloys), including, but not limited to, alloy 625, or any combinationthereof.

Additional thermoacoustic housing components can include TBT, which canbe made from materials including, but not limited to, aluminum, steel,cast steel, forged steel, stainless steel (e.g., 304, 316, 316L, 316H,410, and 419), carbon steel, and alloys, including, but not limited to,nickel-based alloys (e.g., INCONEL® alloys), including, but not limitedto, alloy 625, or any combination thereof. The length of the TBT shouldbe greater than the peak-to-peak displacement of the gas at highamplitude, and the inside surface of the TBT can also be polished. TheTBT can include at least one flow straightener and/or tapering, whichmitigates Rayleigh streaming (see, e.g., U.S. Pat. No. 5,953,920). If aninertance tube is required, the inside surface can be polished, and apressure balancing sliding joint can be included to reduce stress due tothermal expansion. A max flux suppressor (e.g., jet pump) can also beincorporated in the resonator to mitigate Gedeon streaming (see, e.g.,U.S. Pat. No. 6,032,464). Further embodiments can include an additionalambient exchanger for residual heat leakage and multiple tori matedtogether in various ways. Iterations incorporating any single component(or different combinations) are also possible.

The resonating piston can have various shapes, including, but notlimited to, flat, truncated cone, cross-section of an isoscelestrapezoid, concave, convex, or hemi-ellipses, can also have a variety ofsizes, can be hollow, and can be made from the same materials as thethermoacoustic housing. Both the resonating piston and thermoacoustichousing cylinder liner can be coated with an anti-friction compound,such a thermoplastic polymer. While not shown in the above mentionedfigures, sealing and/or guidance rings, which can also be coated with ananti-friction compound, can be seated in the resonating piston head.Rings can be any size, cut (e.g., angle, step, and butt), style (e.g.,pressure balanced, single, and multi-segment), and made from anysuitable composite plastic material (i.e. thermoplastic polymer),including, but not limited to, polytetrafluoroethylene (“PTFE”),polyetheretherketone (“PEEK”), and/or polyphenylene sulfide (“PPS”). Thecomposite plastic material can also use fillers including, but notlimited to, white glass, glass molybdenum (“glass moly”), glassgraphite, carbon, PEEK, bronze, bronze molybdenum (“bronze moly”), PPS,molybdenum, and in any combination thereof. As an alternative to pistonand/or guide rings, the resonating piston head/thermoacoustic housingcould also incorporate a gas/fluid bearing, which can be of a designincluding, but not limited to, hydrostatic, hydrodynamic, or anycombination thereof (discussed below). Replaceable cylinder liners canalso be used with the resonating and/or compression piston head. Whilenot shown, a means of piston displacement control and return, which caninclude, but is not limited to, one or more springs (gas, mechanical, orany combination thereof), can set between the resonating piston and thepiston rod aperture (or any other location in the thermoacoustichousing); a valved porting means may also be incorporated.

Pressure packing, lubrication wiper packing, or any other type of seal,can be set around the piston rod where the rod penetrates thethermoacoustic housing, compression housing, and/or distance housing (orin any other location). The packing can also abut or penetrate theapposing housing. A purging canister, which can contain the same gas asthat in the thermoacoustic housing, purging line, and/or venting tubecan also be included. The pressure packing can be of the water-cooled ornon-water-cooled variety (e.g., Thermosleeve™).

The compression housing, piston, piston rod, and distance housing can bemade from materials including, but not limited to, ceramic, iron, castiron, nodular cast iron, ductile iron, gray iron, aluminum, steel, caststeel, forged steel, stainless steel (e.g., 304, 316, 316L, 316H, 410,and 419), carbon steel, bronze, and alloys, including, but not limitedto, nickel-based alloys (e.g., INCONEL® alloys), including, but notlimited to, alloy 625, or any combination thereof. Just as with theresonating piston head, the compression piston head, piston rings, guiderings, and/or compression housing cylinder liner may be coated with ananti-friction compound, such as a thermoplastic polymer. Furthermore,the compression piston can be hollow, and use gas bearings of anyvariation. The distance and compression housing may also have multiplesealable access holes and a means of piston displacement control andreturn, which can include, but is not limited to, one or more springs(gas, mechanical, or any combination thereof) in multiple housings.Additionally, all of these components and others, such as replaceablecylinder liners, inlet/discharge valves, which can be corrosionresistant (e.g., stainless steel, engineered plastics) and of reed,one-way check, channel, concentric ring, ported plate, or poppet valvedesign, are all commercially available. Finally, all mating surfaces forthermoacoustic, distance, and compression housings not only providefirst, second (via packing/strips), or no support to the piston rod, butcan also provide means for guiding the reciprocating rod linearly andinhibiting radial movement.

FIG. 3 schematically illustrates one embodiment of a TADC 300 interfacedwith a gas turbine 301. In this embodiment, the gas turbine 301 has twoshafts (mechanical drive). The first shaft assembly 302 of the gasturbine 301 includes a compressor 303 (intercooler not shown), acombustor 304, and a high pressure (“HP”) turbine 305 (first part of twopart expander). A power turbine 306 (second expander) is attached to thesecond shaft 307. This turbine 306 drives a mechanical device 308, whichin this embodiment is a centrifugal compressor, such as for a gaspipeline. Other mechanical devices (on or offshore) include, but are notlimited to, an electric generator or a pump (not shown).

To initiate the process, air is compressed in the compressor 303. Thecompressed air is then piped via flow path 309 to the combustor 304,where the air is mixed with fuel and ignited. The expanding gas drivesboth the HP turbine 305 and the power turbine 306. Exhaust heat exitingthe gas turbine can be channeled via flow path 310 and optional valve311 into a heat recovery unit (“HRU”) 312. Concurrently, circulatingfluid (via optional pump 313) can be pumped via flow path 314 into theHRU. The circulating fluid is heated via the exhaust and then piped viaflow path 315 into the hot exchanger of the TADC 300. While not shown,cold fluid can also delivered (pump optional) into the cold exchanger ofthe TADC 300, and an additional exchanger and fan may also be includedfor cooling the cold fluid with ambient air.

The temperature gradient between the hot and cold exchangers of the TADC300 powers the TADC 300. As a result, air is sucked through filter 316and refrigeration unit 317 (optional) and compressed in TADC 300. The“free compressed air” is then channeled to a pulsation bottle 318, wherethe air flow is evened out. The compressed air can then be piped viaflow path 319 to the HRU 312, where the air is further heated. At thispoint, the air can be directed via valves 320, 321, 322 and 323 to anystage, in any quantity, at any pressure, and at multiple locations inthe gas turbine 301, specifically a point before the combustor 304 butafter the turbine compressor 303, for example, prior to the NOxequipment (valve 320), the combustor 304, the HP turbine 305 (valves 321and 322), and between the HP turbine exhaust outlet and power turbineinlet (valves 321 and 323). While not shown, other points include theturbine compressor 303, after the combustor 304 but before the HPturbine 305, the power turbine 306, a recuperator (if used) or somecombination thereof. If a single shaft is used (not shown), air can alsobe directed to multiple points. The “free compressed air” improves theefficiency of the gas turbine 301 over various loads, as the work usedto create the “free compressed air” was not obtained from the compressor303 of the gas turbine 301. Said another way, the TADC 300 reduces theamount of CO₂ emitted per a given unit of energy produced from a gasturbine, allowing companies the potential to earn carbon credits in acarbon regulated environment. In addition, the TADC 300 allows for theuse of heat that otherwise would be vented and lost from the gas turbine301. The use of the TADC 300 thus means that the efficiency of thecompressor 303 may be increased, thereby reducing the amount of naturalgas needed for the compressor 303 in a gas pipeline. This results inlower costs for the operator of a gas pipeline using a TADC 300 with thecompressor 303.

FIG. 4A provides detail for a variation of a single-actingnon-lubricated compression piston head 118B for TADC 101 shown inFIG. 1. This compression piston head 118B contains a sealing ring 130seated in a groove 131 in compression piston head 118B and coaxial withthe axis of the piston and cavity side wall, thereby preventingcompressed gas/fluid from leaking from the compression chamber 119between the compression piston head 118B and the inner surface of thecompression housing 117. A biasing means 132 of forcing the sealing ring130 to stay in contact with the inner surface of the compression housing117 can also be included, if such a device is not incorporated insealing ring 130. To prevent the piston from coming into contact withthe inner surface of the compression housing 117, at least one seatedguide ring 133 (e.g., a rider ring) can be utilized, which is seated ina second groove 134 in the compression piston head 118B. As with thesealing ring 130, the guide ring 133 is coaxial with the axis of thecompression piston head 118B and the inner surface of the compressionhousing 117.

FIG. 4B demonstrates one embodiment of a single-acting non-lubricatedcompression piston head 118C utilizing a hydrostatic gas/fluid bearingwith TADC 101 shown in FIG. 1. The basic operating characteristics arethe same as those mentioned earlier. However, as compression piston head118C moves forward (to the right in FIG. 1), some of the pressurizedprocess gas/fluid (e.g., air) in the compression chamber 119 isdelivered to a clearance gap between the outer wall of compressionpiston head 118C and the inner wall of compression housing 117, therebyproviding a gas bearing. The delivery system can include, but is notlimited to, at least a first aperture 135, a passageway 136, a secondaperture 137, a circumferential groove 138, which is set about the outerwall of compression piston head 118C, or some combination thereof. Whilenot shown, another example could have multiple branches originating frompassageway 136 to additional apertures in fluid communication withcircumferential groove 138. In yet another embodiment, the compressionpiston incorporates a one-way valve with the first aperture 135, areservoir, and multiple apertures in the compression piston head atangularly spaced locations around the circumference of the slidingcompression piston, all of which are in fluid communication with thereservoir; however, in this case no circumferential groove is required(see, e.g., U.S. Pat. No. 5,525,845). The gas bearing in FIG. 4B canalso be used with a double-acting piston (not shown) as described above(or in any other single/double-acting iteration described below; notshown); however, at least a second set of apertures (not shown), anotherpassageway (not shown), and a second circumferential groove (not shown)delivering gas/fluid (not shown) from the opposite compression chamber(not shown) would be required (see, e.g., U.S. Pat. No. 4,932,313).Conversely, pressurized gas/fluid from the compression housing 117 canbe delivered to the clearance gap via a system that is part of thecompression housing (discussed in greater detail in FIG. 4C). In thisexample, at least one radial aperture (entrance; not shown) and at leastthree radial apertures (exit; not shown) would be required. Furthermore,the three radial apertures (not shown) would be formed in thecompression housing 117 at angularly spaced locations around thecircumference of the sliding compression piston head 118C (multiple setsare also possible). Connecting the entrance and exit apertures (notshown) is at least one passageway (not shown), which can be within, ontop of, or in-between separate compression housings. This alternativecould also use at least one one-way valve (not shown), a reservoir (notshown), and compressed gas/fluid (not shown) from an external source(not shown), such as a tank, a gas turbine bleed line, an on-siteelectrical compressor, a turbine-driven centrifugal compressor, areciprocating compressor, a rotary compressor, a screw compressor, orother type of compression equipment/plant processes.

FIG. 4C provides detail to one embodiment of a resonating piston headfor TADC 101 shown in FIG. 1 further including hydrostatic gas/fluidbearings. As shown in FIG. 4C, the pressurized working gas/fluid isdrawn from the variable-volume chamber 139 to the right of theresonating piston head 107; however, the pressurized fluid could also bedrawn from the opposing variable-volume chamber 140, or both. As theresonating piston head 107 moves to the right, the working gas/fluid inthe variable-volume chamber 139 increases in pressure; this increase inpressure forces some of the gas/fluid through the aperture 141 andone-way valve 142 into reservoir 143. Seeking areas of lower pressure,the pressurized fluid in the reservoir 143 is dispersed viapassageway(s) 144 and at least three radial apertures (exit) 145 in thethermoacoustic housing 102. The radial apertures 145 can be formed atangularly spaced locations around the circumference of the slidingresonating piston head 107. Furthermore, multiple sets of radialapertures 145 in fluid communication with passageway(s) 144 are alsopossible. As the pressurized fluid is released from the radial apertures145, it is directed to a clearance gap in-between outer wall ofresonating piston head 107 and inner wall of thermoacoustic housing 102,thereby providing a gas bearing. In this example the reservoir 143 andpassageway(s) 144 are located within the thermoacoustic housing cylinderwall; however, other iterations can have these components within, on topof, or in-between separate compression housings (see, e.g., U.S. Pat.No. 6,293,184). In another embodiment, the one-way valve 142 and/orreservoir 143 may not be required. Furthermore, the pressurized fluidcan be delivered to the clearance gap from both variable-volume chamberssequentially. A hydrostatic gas bearing may include, but is not limitedto, any component discussed above, use a separate dedicated pump, and anaperture further consisting of orifices and/or porous media (e.g.,carbon, bronze or steel), or some combination thereof. Finally, any gasbearing design as described in FIG. 4B and FIG. 4C can be used with anyresonator piston head, even if resonator is attached to a lubricatedcompression piston head.

FIG. 5 shows an embodiment of a single-acting lubricated standing waveTADC 500. This TADC is similar to the TADC shown in FIG. 1, except thatthe compression housing 501 differs from that shown in FIG. 1.Compression housing 501 contains compression piston head 502, which islubricated by a pressurized lubricating system 503. In this embodiment,pressurized lubricating system 503 comprises pump 504, lubricant line505, and lubricant recovery line 506. In addition to a compressionchamber 507, compression housing 501 defines a cavity 508 for collectinglubricant, where it feeds into lubricant recovery line 506. While notshown, a pressurized lubricating system can also include items such as alubricant filter, a lubricant dispenser, and a spray nozzle. Finally,lubricant wiper packing may be substituted for pressure packing.

FIG. 6 shows a variation of a single-acting lubricated compressionpiston head 600 for use with the lubricated TADC 500 shown in FIG. 5. Toremove lubricant from the cavity wall, the compression piston head 600utilizes a scraper ring 601. The scraper ring can be made from metal(e.g., cast iron or aluminum) or metal alloy. Scraper ring 601 channelslubricant into a port 602, which directs the lubricant to the portion ofthe compression housing (501 in FIG. 5) comprising a cavity (508 in FIG.5) for collecting the lubricant. As with the non-lubricated piston head,the lubricated compression piston head 600 also comprises a sealing ring603 seated in a groove 604 in compression piston head 600 and coaxialwith the axis of the compression piston head 600 and the inner surfaceof the compression housing (501 in FIG. 5), thereby preventingcompressed gas/fluid from leaking from the compression chamber (507 inFIG. 5) between the compression piston head 600 and the inner surface ofthe compression housing (501 in FIG. 5). A biasing means 605 for forcingthe sealing ring 603 to stay in contact with the inner surface of thecompression housing (501 in FIG. 5) can also be included, if such adevice is not incorporated in sealing ring 603. To prevent thecompression piston head 600 from coming into contact with the innersurface of the compression housing (501 in FIG. 5), at least one seatedguide ring 606 can be utilized, which is seated in a second groove 607in the compression piston head 600. As with the sealing ring 603, theguide ring 606 is coaxial with the axis of the compression piston head600 and the inner surface of the compression housing (501 in FIG. 5).

The TADC 500 shown in FIG. 5 utilizes lubricant in a closed loop system,and as a result, very little lubricant seeps into the compressed fluidor gas stream. However, a single or double-acting TADC 500 of anyvariation can utilize “once through” lubrication, wherein new lubricantis continuously force-fed into the compression chamber. In suchembodiments, a scraper ring and cavity are not required. In “oncethrough” lubrication, the lubricant lubricates the compression pistonhead and exits through the exhaust port with the compressed processgas/fluid. Upon exit, a means, such as a coalescer, can be used toseparate the lubricant from the compressed processed gas/fluid.

As mentioned above, for control of piston displacement and return, aspring (gas (like spring 232 in FIG. 2), mechanical (like spring 111 inFIG. 1), or combination thereof) can be used in any or multiplehousings. However, if a spring(s) is deemed not sufficient, as describedbelow an additional thermoacoustic engine (housing and engine core), asdescribed herein, can be attached to the top of the single- ordouble-acting TADC compression housing (see, e.g., FIG. 7). Also, adistance housing (like housing 728 in FIG. 7), as described herein, canseparate the compression housing from the second thermoacoustic engine.Inside the additional housing(s), a tandem rod and resonating pistoncombination is mated to the top of the single-acting or double-actingcompression piston (see, e.g., FIG. 7). In essence, a secondthermoacoustic engine is utilized, can be in conjunction with aspring(s) (gas, mechanical, or combination thereof) in any or multiplehousings, to force the piston back. A porting means can also be included(not shown).

FIG. 7A shows one embodiment of a double-acting non-lubricatingtraveling wave TADC 700 with two thermoacoustic housings 701 and 702,each of which comprise a pressurized compressible working gas/fluid 703and 704. Thermoacoustic housings 701 and 702 each incorporate aregenerator 705 and 706 in the thermoacoustic engine core 707 and 708.While not shown, one or more TBTs can also be incorporated adjacent tothe hot exchanger, thereby mitigating heat leaks (and correspondingefficiency loss) from the hot exchanger to ambient. Additionally, thethermoacoustic housings 701 and 702 are of a torus configuration thatincorporate a compliance portion 709 and 710 and an inertance tube 711and 712. In the depicted traveling wave embodiment, the cold exchangers713 and 714 are upstream of the hot exchangers 715 and 716. When the hotexchangers 715 and 716 and cold exchangers 713 and 714 are connected tohot sources 717 and 718 and cold sources 719 and 720, respectively, atemperature differential is created between the two exchangers. Thistemperature differential enables the regenerators 705 and 706 to amplifyincoming acoustic power (not visibly shown, but represented by 721 and722) and pump acoustic power out of the hot exchangers 715 and 716. Thisacoustic power is used to drive the linearly resonating piston heads 723and 724, which are connected to piston rods 725 and 726, and provide newacoustic power to the cold exchangers 713 and 714 via the inertancetubes 711 and 712 and compliance portions 709 and 710.

The distance housings 727 and 728 contain a continuation of the linearlyreciprocating piston rods 725 and 726. Additionally, pressure packings729 and 730, each with an accompanying purging canister 731 and 732 anda purging line 733 and 734, can be set about the piston rods 725 and 726and the piston rod apertures 754, 755, 756, and 757, in the distancehousings 727 and 728, and pressure packings 735 and 736, each with anaccompanying vent tube 737 and 738, can be set about the piston rods 725and 726 and the piston rod apertures in the distance housings 727 and728.

Compression housing 739 incorporates a double-acting compression pistonhead 740. The compression housing 739 and double-acting compressionpiston head 740 define two compression chambers 741 and 742. Compressionhousing 739 also comprises the remaining portion of piston rods 725 and726, sealing and/or guide rings (discussed below), water jackets 743 and744, gas/fluid inlet valves 745 and 746, gas/fluid discharge valves 747and 748, gas/fluid inlet ports 749 and 750, and gas/fluid dischargeports 751 and 752.

To start TADC 700, a starting mechanism 753 can be used to propelcompression piston head 740 forward (to the right in FIG. 7A). As aresult, the process gas/fluid in compression chamber 742 is compressed.When the pressure in the compression chamber exceeds the dischargepressure, the process gas/fluid is released via the discharge valve 748.This also opens inlet valve 745 so that process gas/fluid can entercompression chamber 741. On the return stroke, powered by thetemperature differential created in thermoacoustic engine core 708,traveling acoustic wave 722 propels linear resonating piston head 724(to the left in FIG. 7A). As the compression piston head 740 isconnected to piston rod 726, the force applied to the resonating pistonhead 724 propels the compression piston head 740 forward (to the left inFIG. 7A). As a result, the process gas/fluid in compression chamber 741is compressed. When the pressure in the compression chamber exceeds thedischarge pressure, the process gas/fluid is released via the dischargevalve 747. This also opens inlet valve 746 so that new gas/fluid canenter compression chamber 742. It is also to be understood that ifpiston head 740 has difficulty initially moving forward (to the right inFIG. 7A), discharge valve 748 can be configured to open sooner, therebyreducing the load on compression piston head 740. Similarly, on thereturn stroke, discharge valve 747 can also be configured to opensooner.

The starting mechanism 753 for TADC 700 (and 800 and 900 discussedbelow) can take a variety of different forms. For example, compressedair could be injected into one or both (in alternating sequence) sidesof the compression piston head 740 via a separate delivery system or thevalved inlet ports 749 and 750. Compressed air could also be applied toan expansion unit (not shown) in one or both of the distance pieces 727and 728. The sources for the compressed air could include an air tank, agas turbine bleed line, an on-site electrical compressor, aturbine-driven centrifugal compressor, a reciprocating compressor, arotary compressor, a screw compressor, or other type of compressionequipment/plant processes (not shown). Additionally, compressed workingfluid could be injected into one or both thermoacoustic housings 701 and702 between the resonating piston head 723 and 724 and housing 701 and702 (via a purging canister, not shown). Another means of startingoscillation would be to insert a magnet (not shown) in the compressionpiston head 740 and a coil at both ends of the compression housing 739,and alternate electric voltage between both ends.

FIG. 7B shows one variation of a double-acting non-lubricated/lubricatedcompression piston head 760, which could be used with TADC 700 or anyother double-acting TADC. In this embodiment, two seated sealing rings761 and 762 are located at the center of compression piston head 760,while at least two guiding rings 763 and 764 are located on oppositesides of the sealing rings 761 and 762. A means (not shown) of forcingthe sealing rings 761 and 762 to stay in contact with the inner surfaceof the compression housing 739 can also be included, if such a device isnot incorporated in the sealing rings 761 and 762. Another optionincludes incorporating at least one sealing ring at both ends (notshown) of the compression piston head 740, and a means of forcing thesealing rings to stay in contact with the inner surface of thecompression housing 739.

FIG. 8 provides one embodiment of a double-acting lubricated cascadedTADC 800. In this embodiment, thermoacoustic housings 801 and 802 caneach be approximately 1 acoustic wavelength long (the same length as thewavelength of the acoustic wave) and contain pressurized compressibleworking fluid. Furthermore, both thermoacoustic housings 801 and 802comprise at least one stack-based thermoacoustic engine core (803 and804, respectively), which is used to initiate an acoustic pressure wave(not visible, but represented by 805 and 806, respectively) and at leastone regenerator-based thermoacoustic engine core (817 and 818,respectively). Each stack-based thermoacoustic engine core (803 and 804)comprises a hot exchanger (807 and 808, respectively) connected to a hotsource (809 and 810, respectively) and a cold exchanger (811 and 812,respectively) connected to a cold source (813 and 814, respectively).Stacks (815 and 816, respectively) are located between the hotexchangers (807 and 808, respectively) and the cold exchangers (811 and812, respectively). Separating the stack-based engines 803 and 804 fromthe regenerator-based thermoacoustic engines (817 and 818, respectively)can be TBTs (819 and 820, respectively), which mitigate heat leakagebetween the stack-based and regenerator-based thermoacoustic engines.Each regenerator-based thermoacoustic engine core (817 and 818)comprises a hot exchanger (821 and 822, respectively) connected to a hotsource (823 and 824, respectively) and a cold exchanger (825 and 826,respectively) connected to a cold source (827 and 828, respectively).Regenerators (829 and 830, respectively) are located between the hotexchangers (821 and 822, respectively) and the cold exchangers (825 and826, respectively). Also shown in thermoacoustic housing 801 is anoptional ambient exchanger 831 (can be used in both housings).Regenerators 829 and 830 amplify the acoustic power (not visible, butrepresented by 832 and 833, respectively) created by stack-based engines803 and 804. This acoustic power is used to drive the linearlyresonating piston heads 834 and 835, which are connected to piston rods836 and 837.

The distance housings 838 and 839 contain a continuation of the linearlyreciprocating piston rods 836 and 837. Additionally, pressure packings840 and 841, each with an accompanying purging canister 842 and 843 anda purging line 844 and 845, can be set about the piston rods 836 and 837and the piston rod apertures 864, 865, 866, and 867, of the distancehousings 838 and 839, and pressure/lubricating packings 846 and 847,each with an accompanying vent tube 848 and 849, can be set about thepiston rods 836 and 837 and the piston rod apertures of the distancehousings 838 and 839.

Compression housing 850 incorporates a double-acting compression pistonhead 851. The compression housing 850 and double-acting compressionpiston head 851 define two compression chambers 852 and 853. Compressionhousing 850 also comprises the remaining portion of piston rods 836 and837, sealing and guide rings (discussed above), gas/fluid inlet valves854 and 855 and gas/fluid discharge valves 856 and 857, and gas/fluidinlet ports 858 and 859 and gas/fluid discharge ports 860 and 861.Compression housing 850 also comprises lubricating system 862 comprisingpump 863 and lubricant line 869 (lubricant dispenser and filter notshown).

To start TADC 800, a starting mechanism 868 can be used to propelcompression piston head 851 forward (to the right in FIG. 8). As aresult, the gas/fluid in compression chamber 853 is compressed. When thepressure in the compression chamber exceeds the discharge pressure, theprocess gas/fluid is released via the discharge valve 857. This alsoopens inlet valve 854 so that process gas/fluid can enter compressionchamber 852. On the return stroke, the amplified traveling acoustic wave833 propels linear resonating piston head 835 (to the left in FIG. 8).As the compression piston head 851 is connected to piston rod 837, theforce applied to the resonating piston head 835 propels the compressionpiston head 851 forward (to the left in FIG. 8). As a result, theprocess gas/fluid in compression chamber 852 is compressed. When thepressure in the compression chamber exceeds the discharge pressure, theprocess gas/fluid is released via the discharge valve 856. This alsoopens inlet valve 855 so that new process gas/fluid can entercompression chamber 853. It is also to be understood that if piston head851 has difficulty initially moving forward (to the right in FIG. 8),discharge valve 857 can be configured to open sooner, thereby reducingthe load on compression piston head 851. Similarly, on the returnstroke, discharge valve 856 can also be configured to open sooner.

FIG. 9 demonstrates another embodiment of a double-acting lubricatedcascaded TADC 900. TADC 900 is similar to TADC 800 shown in FIG. 8,except that the thermoacoustic housings 901 and 902 and distancehousings 903 and 904 differ from those shown in FIG. 8 (thermoacoustichousings 801 and 802, and distance housings 838 and 839). Thermoacoustichousings 901 and 902 each comprise two different cross-sectional areas(905 and 906, and 907 and 908, respectively) with each cross sectionalarea having a length of approximately ¼ acoustic wavelength. The portionof the thermoacoustic housings with the smaller cross-sectional area(905 and 907, respectively) can comprise a stack-based thermoacousticengine core (909 and 910, respectively), and the portion of thethermoacoustic housings with the larger cross-sectional area (906 and908, respectively) can comprise a regenerator-based thermoacousticengine core (911 and 912, respectively). As detailed in FIG. 8, above,the stack-based thermoacoustic engine cores 909 and 910 are used toinitiate an acoustic pressure wave (not visible, but represented by 943and 944, respectively). Each stack-based thermoacoustic engine core (909and 910) comprises a hot exchanger (913 and 914, respectively) connectedto a hot source (915 and 916, respectively) and a cold exchanger (917and 918, respectively) connected to a cold source (919 and 920,respectively). Stacks (921 and 922, respectively) are located betweenthe hot exchangers (913 and 914, respectively) and the cold exchangers(917 and 918, respectively). Separating the stack-based engine cores 909and 910 from the regenerator-based thermoacoustic engine cores (911 and912, respectively) can be TBTs (923 and 924, respectively), whichmitigate heat leakage between the stack-based and regenerator-basedthermoacoustic engine cores. Each regenerator-based thermoacousticengine core (911 and 912) comprises a hot exchanger (925 and 926,respectively) connected to a hot source (927 and 928, respectively) anda cold exchanger (929 and 930, respectively) connected to a cold source(931 and 932, respectively). Regenerators (933 and 934, respectively)are located between the hot exchangers (925 and 926, respectively) andthe cold exchangers (929 and 930, respectively). Regenerators 933 and934 amplify the acoustic power (not visible, but represented by 935 and936, respectively) created by stack-based engines 909 and 910. Thisacoustic power is used to drive the linearly resonating piston heads 937and 938, which are connected to piston rods 939 and 940. Distancehousings 903 and 904 differ from those shown in FIG. 8 (838 and 839) bythe inclusion of a mechanical spring (941 and 942, respectively). Thisspring can also be gas, or combination thereof, and can also be presentin multiple locations in the distance, thermoacoustic, and compressionhousings. A porting means, which can be valved, could also beincorporated.

Cascaded thermoacoustic engines (engines and housings) of any variation(see, e.g., U.S. Pat. No. 6,658,862) can be used to power bothresonating piston heads 937 and 938. With the cascade design, astack-derived thermoacoustic engine core can be used to initiate theacoustic pressure wave, and exchangers can be arranged in any order. Aregenerator-derived engine core is used to amplify the acoustic powergenerated from the stack. In certain embodiments, the TBT can actuallyconnect the stack-based thermoacoustic engine core and theregenerator-based thermoacoustic engine core. In general, the TBT is atleast as long as the peak-to-peak displacement of the gas/fluid and canalso be tapered (see, e.g., U.S. Pat. No. 5,953,920). For additionalpower, one or more stacks, regenerators, or TBTs in any combination canbe added in series, and a bellows can be added to accommodate thermalexpansion and contraction of the various components. Flow straightenersand additional ambient exchangers may also be added. If heat leaks areexcessive, a second housing can encase the thermoacoustic housing. Thethermoacoustic housing (resonating tube) can extend beyond the secondhousing, although this generally requires the use of seals. The secondhousing can be pressurized to a similar pressure as that of thethermoacoustic housing, and can also contain insulation.

The stacks and regenerators within the thermoacoustic housings shouldgenerally be placed in a region of the acoustic wave of high specificacoustic impedance. It is also possible to have multiple regions of highspecific acoustic impedance along an axis in the thermoacoustic housing(e.g., a housing that is 1 acoustic wavelength long). In such a case,each region could contain adjacent multiple stacks, TBTs, and/orregenerators (which could be connected) in series and in any combinationthereof. A means of creating multiple regions of high specific acousticimpedance would be to insert an approximately ½ acoustic wavelengthresonator of different cross-sectional area between the approximately ¼acoustic wavelength resonators as shown in FIG. 9 (indefinite ½ acousticwavelength extensions, and other extension lengths, are possible).Additionally, between at least two regions of high specific acousticimpedance a side branch and bulb combination, which is generallyorthogonal to the axis of the resonator, can also be added to thethermoacoustic housing, thereby providing axially extended regions withhigh specific acoustic impedance (see, e.g., U.S. Pat. No. 6,658,862).Finally, this extended region can be further extended by periodicallyadding additional side branch and bulb combinations. For additionalbalance, these side branches can be on both sides of the resonator atthe same axial location.

FIG. 10 describes an optional design of a thermoacoustic end-housing1000 with an expanded compliance section 1001 (see, e.g., U.S. Pat. No.6,658,862), which can be used with an embodiment of a TADC 900 as shownin FIG. 9. The circumference of the piping 1002 may expand as itapproaches and penetrates into the expanded compliance section 1001,thereby lowering the velocity of the gas coming from the compliancesection 1003.

For multistage compression, multiple TADCs of any variation can be matedtogether in any orientation. Piping, with inter-cooling and optionalcoalescer/scrubber, connects the discharge ports to the inlet ports,allowing for the transmission of compressed air. If desired, arefrigerator (including thermoacoustic and Sterling refrigerators) or adesiccant dryer can also be incorporated to dehumidify the air aftercompression.

As described in one embodiment in FIG. 11, another means of creatingmultistage compression (or additional capacity) comprises mating asecond compression housing to the compression housing of a single ordouble-acting TADC with one thermoacoustic engine; a second distancepiece, accompanying pressure packing, purging canister, purging line,and/or vent tube, as described herein, can also be included. Inside, atandem single or double-acting compression piston head and piston rodwould be mated to the master piston of the TADC. Such embodiments arenot limited to one additional compression housing and distance piece,and depending on need (multistage or capacity), tandem compressionpiston can vary in size. Also, if the tandem compression piston isdouble-acting, the second compression chamber would have more than onevented inlet and outlet port.

FIG. 11 describes one embodiment of a tandem single-actingnon-lubricated TADC 1100 with one thermoacoustic engine (not shown).This embodiment incorporates a first compression housing 1101 and asecond compression housing 1102. First compression housing 1101comprises a first compression piston head 1103, which is attached to afirst piston rod 1104 and a second piston rod 1105. First compressionhousing 1101 and first compression piston head 1103 define a firstcompression chamber 1106. First compression housing 1101 also comprisespiston and guide rings (not shown), water jackets 1107 and 1108(optional), gas/fluid inlet valve 1109, gas/fluid discharge valve 1110,gas/fluid inlet port 1111, and gas/fluid discharge port 1112. Secondcompression housing 1102 comprises a second compression piston head1113, which is attached to the top end of the first compression pistonhead 1103 via the second piston rod 1105. The second compression housing1102 and second compression piston head 1113 define a second compressionchamber 1114. Second compression housing 1102 also comprises piston andguide rings (not shown), water jackets 1115 and 1116, gas/fluid inletvalve 1117, gas/fluid discharge valve 1118, gas/fluid inlet port 1119,and gas/fluid discharge port 1120. Second compression housing 1102 alsocomprises pressure packing 1121, with an accompanying purging canister1122 and a purging line 1123 set about the second piston rod 1105 andthe mating surface of the first compression housing 1101; while notshown, a vent tube may be used in lieu of a purging canister and purgingline. In this embodiment, as with the other types of multistagecompression, the gas/fluid discharge port 1112 of the first compressionhousing 1101 can be connected via piping 1124 to the gas/fluid intakeport 1119 of the second compressor housing 1102. In other embodiments,inter-cooling, lubrication, scrubbers, dehumidification, and coalescers(not shown) can also be utilized.

The TADC as discussed in FIG. 7A, as well as other embodiments (e.g.,FIG. 8, and FIG. 9), could also be further expanded to generatemultistage compression (or additional capacity). In this case (notshown), as described herein, at least one additional compressionhousing, compression piston (piston size and housing will vary dependingon purpose), piston rod, pressure/lubrication wiper packing with eitherpurging canister and line or venting tube, and distance housing(optional) could be inserted between the compression housing and thesecond thermoacoustic housing or distance housing. Inter-cooling,coalescers, dehumidification, and scrubbers (not shown) can also beutilized.

A means (not shown) of condensing process gas/fluid (e.g., air), such asrefrigeration (which can be thermoacoustic or Sterling refrigeration),can also be attached to the inlet port of a single or multistage TADC ofany variation, thereby allowing greater volumes of process gas/fluid tobe compressed. Filter(s) (not shown) can also be added to the inlet portto clean the process gas/fluid. Pulsation tubes (not shown) can also beused to even out the flow of processed gas/fluid from the TADC; thepulsation tubes can be directly attached to TADC. The compressedgas/fluid can also be stored (not shown) before use and a Heat RecoveryUnit (HRU)/exchanger or similar device (not shown) can be used to heatthe compressed gas/fluid before use. Finally, valves (not shown) can beused in any location for controlling flow of process gas/fluids.

FIG. 12A and FIG. 12B schematically demonstrate two orientations forcoupling TADCs of any variation, horizontally apposed 1201 (FIG. 12A)and horizontally aligned 1202 (FIG. 12B). When multistage compression isdesired in the orientation shown in FIG. 12A, the gas discharge port1204 of the first TADC 1203 can be connected via flow path 1205 tointercooler 1206, and via flow path 1207 to the gas intake port 1208 ofthe second TADC 1209. When multistage compression is desired in theorientation shown in FIG. 12B, the gas discharge port 1211 of the firstTADC 1210 can be connected via flow path 1212 to intercooler 1213, andvia flow path 1214 to the gas intake port 1215 of the second TADC 1216.The intercooler can reside in a number of different locations other thanthe location shown in FIG. 12A and FIG. 12B. Additional TADC(s)configured in a similar manner can be added to both configurations. Bothorientations can also encompass alternate setups, such as having eachcompression housing on opposite ends. Finally, while not shown, multipleTADC units of any variation can feed into a single TADC.

As noted, the thermoacoustic prime mover in a TADC involves a hot andcold source. Heat can be delivered by any medium, such as copper wiring,preheated gas/fluid, which utilizes piping and possibly a pump, or someother combination/new variation thereof. Furthermore, a heat recoveryunit (HRU)/exchanger or similar device can be used in conjunction with ahot source to facilitate the heating of gas/fluid for the thermoacousticprime mover. As for cooling, a cool gas/fluid may be used. Furthermore;the gas/fluid may be circulated via a cooling system, which may include,but is not limited to, exchangers, fans, and pumps.

With slight modifications, most of the previously discussed singleacting embodiments can be converted to double acting (and vice versa),non-lubricated can be converted to lubricated (and vice versa), and anytype of thermoacoustic engine/housing can be used with any type ofcompression housing.

As noted earlier, a TADC of any variation can be used in conjunctionwith a gas turbine, which could power an on or offshore centrifugalcompressor, an electrical generation set, or pump. The compressed airfrom a TADC may also be injected into an expander, which is attached tothe external shaft of a gas turbine or a separate generation setproviding onsite electricity. Additional TADC gas turbine applicationsinclude ships and tanks.

A gas/diesel engine (stationary or moving) is another type of enginethat can utilize any variation of a TADC to convert waste heat (exhaust)to usable energy. For example, the compressed air could be injected intothe engine's intake tract or used with multistage compression.Alternatively, the compressed air could be applied to an expandergeneration set, which could provide electricity to various electricalapplications. One differentiating factor between a gas turbine and agas/diesel engine is that a gas/diesel engine relies on engine coolant,which is considerably cooler than exhaust gas, to disperse heat. Whilethe use of engine coolant reduces the amount of heat that can beharnessed via exhaust, the engine coolant could be used as a heat sinkfor the thermoacoustic engine (i.e., coolant could be pumped through thecold exchanger).

A TADC system of any variation also holds potential in the manufacturingenvironment. For example, in the coke/iron/steel industry a TADC couldprovide onsite compression or electricity (with expander generation set)by harnessing waste heat emitted from a coke oven, quenching tower,furnace/kiln, sintering plant, ultra high power electric arc furnace, orcasting facility. Additional TADC compression/electrical applications inthe metal industry include refining furnaces (includes ultra high powerelectric) in nickel, aluminum, zinc, and copper plants. Finally, a TADCcan be used with a glass plant (furnace), cement plant (kiln), coalpower plant, ammonia plant, carbon black plant, incinerator, catalyticcracker, drying and baking oven, and heat treating furnace. It is alsoimportant to note that all of these plants/systems emit flue gas.Generally, before this gas can be released into the atmosphere, the gasmust be scrubbed of pollutants. However, the temperature of the gas isoften too hot for the filters to operate; hence, water is used to coolthe flue gas. A TADC system could be used in lieu of water, thus notonly reducing the water consumption, but also improving the energyefficiency of the plant.

A TADC system of any variation also has potential in the alternativeenergy segment. For example, a TADC system could provide low costcompression or electricity (with an expander/generation set) to remotelocations with access to geothermal energy (e.g., abandoned oil wells),thereby preventing costly construction of power lines and reducingwasted energy lost through transmission. Another example would be use ofa TADC with solar concentrators, which could heat tubing containing agas/fluid (e.g., thermal oil). As with geothermal applications, theheated gas/fluid could power the TADC. Finally, many types of fuel cellsexhaust high grade heat, which could also be used with a TADC togenerate additional compression or electricity (with expander/generationset).

All of the devices and methods disclosed and claimed herein can be madeand executed without undue experimentation in light of the presentdisclosure. While the devices and methods of this invention have beendescribed in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to the devicesand/or methods and in the steps or in the sequence of steps of themethods described herein without departing from the concept, spirit andscope of the invention. More specifically, it will be apparent thatcertain agents which are both chemically and physically related may besubstituted for the agents described herein while the same or similarresults would be achieved. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

1. A thermoacoustic compressor, comprising: a) a first housing having afirst end, a second end, an inner wall, and an outer wall, said firsthousing defining a first cavity, and said second end of said firsthousing defining a first piston rod aperture; b) a second housing havinga first end, a second end, an inner wall, and an outer wall, said firstend of said second housing operably connected to said second end of saidfirst housing, said second housing comprising pressurized gas or fluidand defining a second cavity, and said first end of said second housingdefining a second piston rod aperture; c) a reciprocating piston axiallymovable within said first and second cavities, said reciprocating pistoncomprising: i) a compression piston head having a first end, a secondend, and an outer wall, said compression piston head disposed in saidfirst cavity, said first end of said compression piston head and saidfirst end of said first housing defining a first variable-volumechamber, and said second end of said compression piston head and saidsecond end of said first housing defining a second variable-volumechamber; ii) a piston rod having a first end and a second end, saidfirst end of said piston rod connected to said second end of saidcompression piston head; and iii) a resonating piston head having afirst end, a second end, and an outer wall, said resonating piston headdisposed in said second cavity, said first end of said resonating pistonhead and said first end of said second housing defining a thirdvariable-volume chamber, and said second end of said resonating pistonhead and said second end of said second housing defining a fourthvariable-volume chamber, said first end of said resonating piston headconnected to said second end of said piston rod; d) a valved intake portand a valved discharge port on said first end of said first housing; e)a thermoacoustic engine connected to said inner wall of said secondhousing positioned between said second end of said resonating pistonhead and said second end of said second housing; f) a means forinhibiting gas flow between said first and said second housing; g) ameans for providing or delivering heat to said thermoacoustic engine;and h) a means for removing heat from said thermoacoustic engine.
 2. Thethermoacoustic compressor of claim 1, wherein said compression pistonhead comprises at least a first sealing means disposed between saidouter wall of said compression piston head and said inner wall of saidfirst housing.
 3. The thermoacoustic compressor of claim 1, wherein saidcompression piston head is lubricated.
 4. The thermoacoustic compressorof claim 1, further comprising a displacement control and return meanswithin said first housing.
 5. The thermoacoustic compressor of claim 1,wherein said thermoacoustic engine comprises a thermoacoustic core. 6.The thermoacoustic compressor of claim 5, wherein said thermoacousticcore comprises a hot exchanger, a cold exchanger, and a stack.
 7. Thethermoacoustic compressor of claim 5, wherein said thermoacoustic enginecore comprises a hot exchanger, a cold exchanger, and a regenerator. 8.The thermoacoustic compressor of claim 1, wherein said second housingcomprises or defines a torus.
 9. The thermoacoustic compressor of claim1, further comprising a second valved intake port and a second valveddischarge port on said second end of said first housing.
 10. Thethermoacoustic compressor of claim 1, further comprising a third housinghaving a first end, a second end, an inner wall, and an outer wall, saidfirst end of said second housing operably connected to said second endof said third housing, said second end of said first housing operablyconnected to said first end of said third housing, said third housingdefining a third cavity, said first end of said third housing defining athird piston rod aperture, and said second end of said third housingdefining a fourth piston rod aperture.
 11. The thermoacoustic compressorof claim 1, wherein said second housing further comprises a plurality ofthermoacoustic engines in series.
 12. The thermoacoustic compressor ofclaim 1, further comprising a gas or fluid bearing disposed in aclearance gap between said outer wall of said compression piston andsaid inner wall of said first housing.
 13. The thermoacoustic compressorof claim 1, further comprising: a) a third housing having a first end, asecond end, an inner wall, and an outer wall, said third housingdefining a third cavity, said second end of said third housing operablyconnected to said first end of said first housing, and said second endof said third housing defining a third piston rod aperture; b) a secondcompression piston head having a first end, a second end, and an outerwall, said second compression piston head disposed in said third cavity,said first end of said second compression piston head and said first endof said third housing defining a fifth variable-volume chamber, and saidsecond end of said second compression piston head and said second end ofsaid third housing defining a sixth variable-volume chamber; c) a secondpiston rod having a first end and a second end, said first end of saidsecond piston rod connected to said first end of said compression pistonhead, and said second end of said second piston rod connected to saidsecond end of said second compression piston head; and d) a secondvalved intake port and a second valved discharge port on said first endof said third housing.
 14. A thermoacoustic compressor comprising: a) afirst housing having a first end, a second end, an inner wall, and anouter wall, said first housing defining a first cavity, and said secondend of said first housing defining a first piston rod aperture; b) asecond housing having a first end, a second end, an inner wall, and anouter wall, said first end of said second housing operably connected tosaid second end of said first housing, said second housing comprisingpressurized gas or fluid and defining a second cavity, and said firstend of said second housing defining a second piston rod aperture; c) athird housing having a first end, a second end, an inner wall, and anouter wall, said second end of said third housing operably connected tosaid first end of said first housing, said third housing comprisingpressurized gas or fluid and defining a third cavity, and said secondend of said third housing defining a third piston rod aperture; d) areciprocating piston axially movable within said first, second, andthird cavities, said reciprocating piston comprising: i) a compressionpiston head having a first end, a second end, and an outer wall, saidcompression piston head disposed in said first cavity, said first end ofsaid compression piston head and said first end of said first housingdefining a first variable-volume chamber, and said second end of saidcompression piston head and said second end of said first housingdefining a second variable-volume chamber; ii) a first piston rod havinga first end and a second end, said first end of said first piston rodconnected to said second end of said compression piston head; iii) afirst resonating piston head having a first end, a second end, and anouter wall, said first resonating piston head disposed in said secondcavity, said first end of said first resonating piston head and saidfirst end of said second housing defining a third variable-volumechamber, and said second end of said first resonating piston head andsaid second end of said second housing defining a fourth variable-volumechamber, said first end of said first resonating piston head connectedto said second end of said first piston rod; iv) a second piston rodhaving a first end and a second end, said second end of said secondpiston rod connected to said first end of said compression piston head;and v) a second resonating piston head having a first end, a second end,and an outer wall, said second resonating piston head disposed in saidthird cavity, said first end of said second resonating piston head andsaid first end of said third housing defining a fifth variable-volumechamber, and said second end of said second resonating piston head andsaid second end of said third housing defining a sixth variable-volumechamber, said second end of said second resonating piston head connectedto said first end of said second piston rod; e) a first valved intakeport and a first valved discharge port on said first end of said firsthousing; f) a first thermoacoustic engine connected to said inner wallof said second housing positioned between said second end of said firstresonating piston head and said second end of said second housing; g) asecond thermoacoustic engine connected to said inner wall of said thirdhousing positioned between said first end of said second resonatingpiston head and said first end of said third housing; h) a means forinhibiting gas flow between said first and said second housing; i) ameans for inhibiting gas flow between said first and said third housing;j) a means for providing or delivering heat to said first thermoacousticengine; k) a means for providing or delivering heat to said secondthermoacoustic engine; l) a means for removing heat from said firstthermoacoustic engine; and m) a means for removing heat from said secondthermoacoustic engine.
 15. A method of compressing a fluid or gas,comprising: a) introducing a fluid or gas through the valved intake portof the thermoacoustic compressor of claim 1 into the firstvariable-volume chamber of the first cavity; b) running thethermoacoustic compressor of claim 1; thereby compressing said fluid orgas.
 16. The method of claim 15, wherein said compressed fluid or gas isreleased from said first variable-volume chamber through said valveddischarge port.
 17. The method of claim 16, wherein said compressedfluid or gas is introduced into a separate mechanical device.
 18. Themethod of claim 17, wherein said mechanical device is a gas turbine. 19.The method of claim 16, wherein heat is provided to said thermoacousticengine from a separate mechanical device.
 20. The method of claim 19,wherein said heat is waste heat generated by said separate mechanicaldevice.